High-sensitivity and Low-power Flexible Schottky Hydrogen Sensor - PowerPoint PPT Presentation

Poster Session II : IoT Including Nanosensors High-sensitivity and Low-power Flexible Schottky Hydrogen Sensor based on Silicon Nanomembrane Minkyu Cho Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST)

 Hydrogen (H 2 ) is useful as a future clean energy resource and an ideal replacement for fossil fuel  Various applications such as hydrogen vehicle, petroleum refining, glass purification, semiconductor manufacturing etc.  H 2 is flammable at concentrations over 4% by volume, therefore high sensitivity H 2 sensor with fast response time is necessary  Silicon nanomembrane based diode type H 2 sensor was demonstrated exhibiting high sensitivity and low power consumption Source:http://www.hydrogen.energy.gov/systems_integration.html US Department of energy

Advantages of Si High Mobility • Well established processing technique Graphene -> more freedom in sensor design Carbon Nanotubes GaAs, GaN Low flexible rigidity of thin Si *Si Poly-Si a-Si Polymers Good material candidate for Low Mobility high performance flexible/wearable H 2 sensors

 The operation principle of the sensor is based on Schottky barrier lowering effect upon exposure to H 2  H 2 gas molecules are diffused into Pd layer forming Palladium Hydride (PdH x ) at Pd/Si interfaces  Device simulations show that effective current quenching has been occurred in 50 nm thickness SiNM H 2 lowering standby power consumption of the sensor Reduced Si thickness Low standby power consumption

 Excellent mechanical properties  Low thermal budget (< 110 o C)  Applicable to wafer-scale process

 High Sensitivity ( > 700% @ 0.5% H 2 concentration) and Fast Response Time ( τ 10−90 = 22s)  Good Linearity (R 2 > 0.98) and Low Limit of Detection (50 ppm, limited by MFC)

 Minor Increased Sensitivity under Tensile Strain (Piezoresistive property of SiNM)  Good Reliability under Repeated Bending and Selectivity to H 2 among Various Test Gases

 Flexible Pd/Si Schottky diode-based H 2 sensor was demonstrated using SiNM transfer on a plastic substrate.  The sensor shows high H 2 sensitivity and fast response time  A repeated bending test was also performed to test its mechanical durability as a flexible sensor, and high sensitivity and stable device performance were maintained after 10 4 times of repeated bending.  The sensor fabrication process is applicable to wafer-scale.  In conjunction with other types of sensors, the Pd/SiNM diode H sensor with a simple fabrication process would be useful in the future flexible/wearable electronics.